1. Field of the Invention
This invention relates to a method of operating an auger ice-making machine, and more particularly, to a method of operating an auger ice-making machine which feeds by means of an auger screw, while scraping, the ice frozen on an inner wall surface of a refrigeration casing, compresses the frozen ice by means of a push head, and stores in a stocker the compressed ice obtained.
2. Description of the Related Art
In the kitchens of coffee shops, restaurants, and the like, ice-making machines for manufacturing blocks of ice of required shapes have been conveniently used for a long time, and these types of machines include an auger type of ice-making machine used for continuously manufacturing blocks of ice in the form of small pieces such as ice chips or ice flakes. In the auger ice-making machine, when ice-making operation is started with ice-making water stored within a cylindrical refrigeration casing at a required level, the casing is forcedly cooled by a refrigerant circulating through an evaporation pipe connected to a refrigerating system. Hence, the ice-making water starts freezing progressively from an inner wall surface of the casing, and thus thin ice of a laminar form is formed. The refrigeration casing has an auger screw inserted thereinto, and when the auger screw is rotationally driven by an auger motor, the thin ice frozen on the inner wall surface of the casing is fed upward by the auger screw while being scraped into a flake form thereby. While passing through a push head disposed in an upper inner section of the refrigeration casing, the flake-form ice fed by the auger screw is compressed, whereby moisture is removed from the ice and compressed ice (ice) is manufactured. The compressed ice that has thus been obtained is discharged and stored in a stocker.
The foregoing auger ice-making machine has, inside the above stocker, stored-ice detection means including a reed switch capable of detecting a storage level of compressed ice, and is adapted to store a required quantity of compressed ice in the stocker at all times. This is accomplished by conducting control so that when the switch turns on to indicate that the detection means has detected a full state (high level) of the compressed ice in the stocker, ice-making operation is stopped, and so that when the switch turns off to indicate that the detection means has detected a decrease in the quantity of compressed ice within the stocker to a required level (low level) due to ice consumption (discharge from the stocker), the ice-making operation is restarted.
However, the differential between the high level and low level detected by the stored-ice detection means is limited to a small value, and after detection of the high level (i.e., the stop of the ice-making operation), the low level resulting from slight melting of the compressed ice or from a small quantity of discharge thereof is detected prior to the restart of the ice-making operation. After this, since a small quantity of compressed ice is only added during the ice-making operation, a full state (high level) is detected soon and the ice-making operation stops. In this case, compressed ice in an incompletely solidified condition is stored in the stocker initially during the restart of the ice-making operation. Accordingly, if the start and stop of the operation are repeated within a short time period by such control as described above, the quantity of compressed ice in an incompletely solidified condition (so-called scrap ice) in the stocker progressively increases. Since such scrap ice is very soft, it sticks to the inner wall surface of the stocker in the form of a donut, then changing into a block of ice, thus impeding the discharge of compressed ice. In addition, a full-state detection failure could result if the block of ice grows to a level at which the stored-ice detection means is disposed. Therefore, if ice-making operation is continued in that state or the machine remains exposed to a cryogenic atmosphere, the entire stocker encounters the serious trouble of freezing. Furthermore, not only the compressed ice could not only become a mass too large to be discharged from the stocker, but also is indicated the likelihood of damage being caused to the auger motor and other ice-making mechanical sections by significant loading.
For these reasons, Japanese Unexamined Patent Publication No. 2001-141344, for instance, proposes a technology for preventing the above-mentioned repetition of start/stop of ice-making operation within a short time period and hence the occurrence of various trouble, associated with the above-mentioned increase in the quantity of scrap ice, by setting the restarting timing of the operation, based on combined use of the storage level of the compressed ice inside the stocker and other parameters.
According to the technology disclosed in the above Patent Publication, the machine is constructed so as to start counting a previously set delay time (one of the other parameters mentioned above) from the time that the stored-ice detection means detects that the quantity of compressed ice in the stocker has been reduced to a low level by consumption, and restart ice-making operation after the delay time has elapsed. In this case, if the stored-ice detection means is maintained in a full-stocker-state (high-level) detection condition by the occurrence of a block of ice in the stocker, even when the compressed ice is discharged from the machine or melts during that time, counting of the delay time is not started since the stored-ice detection means does not detect a low level. Therefore, the quantity of compressed ice is likely to have significantly decreased by the time the block of ice melts and collapses to cause the stored-ice detection means to detect a low level. Consequently, a shortage of ice could occur since the stocker will have become empty by the time a subsequent delay time elapses.
In addition, although the stocker of the foregoing ice-making machine is heat-insulated, melting of the compressed ice in the stocker with time reduces the storage level, and even if the compressed ice is not discharged, the low level may be detected. Furthermore, the speed at which the ice melts is affected by the ambient temperature of the location at which the ice-making machine is installed, and the melting speed of the ice greatly differs between, for example, the wintertime and the summertime. In this case, for example, if the above-mentioned delay time is set to take a small value fit for the time of the year when ice rapidly melts, such as in the summer, the effect of providing the delay time is not obtainable at the time of the year when ice melts slowly, as in the winter. This is because, despite only a slight quantity of compressed ice decreasing, ice-making operation is restarted and such scrap ice as mentioned above increases. Conversely, it is indicated the problem that if the above-mentioned delay time is set to take a large value fit for the time of the year when ice slowly melts, such as in the winter, the stocker runs out of compressed ice at the time of the year when ice melts rapidly, as in the summer. It becomes necessary for a user, therefore, to perform troublesome and complex operations to optimize the setting of the above delay time according to the particular ambient temperature. If stored-ice detection means for detecting a high level and stored-ice detection means for detecting a low level are disposed spacedly in a vertical direction and the differential between both levels is set to take a large value, repetition of the start/stop of operation within a short time period can be prevented without adjusting the delay time. In this case, however, the number of stored-ice detection means increases, thereby increasing costs, disadvantageously.